Adhesive bonding of alpha-olefin hydrocarbon copolymers



United States Patent F US. Cl. 260-293 6 Claims ABSTRACT OF THE DISCLOSURE An adhesive composition suitable for bonding sulfurcurable, chain-saturated hydrocarbon copolymers to polyamide, polyester or cellulosic substrates which comprises an aqueous dispersion of (a) a chlorosulfonated polyethylene and (b) a resorcinol-aldehyde type resin is disclosed. The hydrocarbon copolymer is adhered to the substrate by coating the latter with the adhesive, drying the coating, and curing the hydrocarbon copolymer while pressing it in contact with the coated substrate. When the substrate is a polyester it is pretreated with (I) a mixture of a polyepoxide and an aromatic polyisocyanate adduct with an overcoating of a mixture of a resorcinol-formaldehyde resin and a vinyl pyridine copolymer latex, or (II) a mixture of 2-pyrrolidine, polyepoxide, alkaline catalyst and a blocked polyisocyanate or formaldehyde.

The adhesives disclosed are useful, e.g., in adhering tire cords in pneumatic tires and the like.

This application is a continuationdn-part of our copending application Ser. No. 359,441, filed Apr. 13, 1964, now abandoned.

This invention relates to a new adhesive composition and its use for bonding a-olefin hydrocarbon polymers to selected materials.

Sulfur-curable, chain-saturated a-olefin hydrocarbon polymers (for example, copolymers of ethylene, propylene and non-conjugated dienes) are acquiring increasing importance today in the manufacture of a wide variety of useful products. Applications such as tires, industrial belts, tarpaulins, and the like require that the polymers be bonded to substrate materials such as nylon and rayon.

The adhesives currently available for bonding these polymers to substrates of this type have not been entirely satisfactory. For example, the customary tire cord dips have provided inadequate bonding. Better results have been obtained by applying an organic solvent solution of selected adhesives over the coated cords, but this procedure is economically undesirable for several reasons. Application of the second coat entails additional labor charges and storage costs. Furthermore, the handling and recovery of the volatile organic solvents used in the coating require extra plant investment and still more operating expense. For reasons of both operating safety and economy, many plants are only equipped at' present to use aqueous dispersions.

It has unexpectedly been found that a sulfur-curable, chain-saturated a-olefin hydrocarbon copolymer can be firmly adhered to a polyamide o'r cellulosic substrate by a one-step coating of the substrate with an aqueous dispersion containing (a) a chlorosulfonated polyethylene and (b) a resorcinol-formaldehyde type resin, drying the coating material, and curing the hydrocarbon copolymer while pressing it in contact with the coated substrate. Moreover, the a-olefin hydrocarbon copolymers can be applied to polyester substrates using the one-step coating described provided that such substrates are treated according to the teachings of Shoaf, US. application Ser. No. 320,605, filed Oct. 29, 1963 or Schwarz, U.S. ap lication Ser. No. 509,436, filed Nov. 23, 1963. The details of such treatments will be discussed hereinafter.

The substrates being bonded to the a-olefin hvdrocarbon polymers include the normally-solid polyamioe, polyester and cellulosic substrates. In a particularlv vamable application of the present invention, these materials are in the form of woven fabrics, tire cords. filaments, s un fibers or blends thereof. Representative examples are the industrial fibers such as nylon, rayon. and polyethylene terephthalate. v

The sulfur-curable, chain-saturated a-olefin hydrocarbon copolymer is generally a copolymer of at least one a-monoolefin having the structure RCH=CH wherein R is hydrogen or alkyl of 1 to 16 carbon atoms (e.g., ethylene, propylene, l-hexene), with at least one nonconjugated hydrocarbon diene (e.g., 1,4-hexadiene). The most preferred class of copolymers include those containing about 20 to weight percent ethylene monomer units. Representative copolymers include ethylene/propylene/1,4-hexadiene; ethylene/1,4-hexadiene; ethylene/ propylene dicyclopentadiene; methylene-Z-norbornene; and ethylene/propylene/1,5 cyclooctadiene. Other suitable monomers, copolymers and preparations are disclosed in US. Patents 2,933,480; 3,000,866; 3,063,973; 3,093,620; 3,093,621; and 3,200,- 174; and French Patents 1,321,029 and 1,371,435; and British Patent 957,105.

One of the important components of the adhesive composition is an aqueous latex of a chlorosulfonated olefin polymer. The chlorosulfonated olefin polymer and their preparation are well known to those skilled in the art, and can be prepared in a number of Ways, e.g., those processes set forth in US. Patents 2,212,786; 2,586,363; 2,646,422; 2,862,917; 2,879,261; 2,972,604; and 2,982,- 759. Preferred polymers are those prepared by chlorosulfonation of polyethylenes having densities from about 0.94 to 0.96 g./cc. and melt indexes of about 0.07 to 4 decigrams/min. (ASTM Method D-123 8-57T). The preferred chlorosulfonated polymers contain about 10 to 26 percent chlorine (preferably 15 to 20%) and about 0.5 to 3 percent (preferably 0.7 to 3%) sulfur, by weight. Polymers prepared by chlorosulfonation using SO Cl seem to yield somewhat less bonding strength.

Suitable latexes are prepared from organic solutions of chlorosulfonated polyethylene in a conventional manner. In a typical and preferred procedure the polymer solution is mixed with Water containing a surface-active agent stable under acidic pH conditions. Removal of the organic solvent from the resulting emulsion gives the latex. Water soluble organic emulsifying agents, or miX- tures thereof, which will give oil-in-water emulsions are used. The term oil-inwater emulsifying agents is well understood by those skilled in the art and is set out in detail in the book Surface Active Agents, Schwarz and Perry, Interscience Publishers, Inc. (1949), pages 9-12, 54, 116-120. Particularly useful anionic emulsifying agents are the sodium salts of long-chain alkyl-substituted aryl sulfonic acids or long-chain alkyl sulfonic acids or long-chain alkyl hydrogen sulfates. A particularly preferred procedure involves the use of a minor proportion of an emulsification modifier, soluble in both the aqueous and the oil phase. A preferred example is isopropanol. The modifier is introduced prior to the formation of the latex; it should not be added to the latex because it can cause coagulation. Those skilled in the art can determine the optimum amount to employ for a particular system. If too little modifier is employed, the resulting latex may not have as fine a particle size as desired. Excessive proportions of modifier may lead to ethylene propylene/5-v coagulum formatioh. Detailed procedures for making latexes are given in U.S. Patent 2,968,637. e

The phenol-aldehyde type resin solution which is the other important component 'of the adhesive composition, is preferably made by reacting formaldehyde (or materials furnishing formaldehyde such as paraformaldehyde), with a phenolic component, e.g., a dihydroxybenzene such as resorcinol, which is preferred. Such resins can be made by procedures familiar to those skilled in the art. The relative proportion of aldehyde to'phenolic component can be varied. ln representative procedures about 0.7 to 2 moles of formaldehyde have been supplied for each mole of resorcinol. The condensation can be carried out under basic conditions, e.g., at a pH in the range 8-9 in the presence of a strong basic material such as an alkali metal hydroxide. For use on rayon, the latex is preferably basic; i.e., a pH of 8-9. For use on nylon, it is preferred to carry outthe condensationfof the resin in the pres; ence" of the chlorosulfonated polyethylene latex at a pH of 7 to 7.5 using NapH or 2:10; the dip made this way should be aged 24-30 hours. Another procedure involves the use of a pre-condensed fesin (eig., Penacolite R- 2170 available from Koppers Co.) condensed with additional formaldehyde at a pH of 7.5 to 8; this dip preparation requires only 2 to 4 hours aging. The mixture of resorcinol, formaldehyde and catalyst is usually allowed to react at'a temperature of about 25 C., but higher temperatures may be employe di to hasten the reaction if desired. For best results when conducting alkaline con-densations, it is essential to stop the'condensation quickly to hold down the molecular weight. Neutralization with acid will do this. The time needed to carry out the 'reac tion can be determined by routine experimentation. The formaldehyde/resoncinol resin can he used at once, if desired.

Analternative procedure involves the in situ preparation of the resorcinol/aldehyde, condensate in the presence of the chlorosulfonated polyethylene latex. In this process the formaldehyde, resorcinol and optionally a basicoxide or hydroxide (e.g., zinc oxide or sodium hydroxide) are'mixed with the chlorosulfonated polyethyl ene latex and the composition subsequently allowed to stand at room temperature until ready for use. Empirical routine testing can be used to find out the amount of time needed to age the composition to get optimum results. About 24 to 30 hours aging is preferred.

The relative proportions of the chlorosulfonated polyethylene and the formaldehyde resorcinol resin in the adhesive can be varied quite widely to suit the needs of the particular application. In representative adhesive compositions about two tosix proportions of chlorosulfonated polyethylene have been employed for every proportion by weight of the phenol-aldehyde type resin.

In the first step of the process of the present invention the substrate (e.g., the fabric) is coated with the aqueous adhesive composition. This composition may be applied in any manner desired, such as by dipping, painting, or by roller coating. The coating is then dried at an elevated temperature such as 135 C. The amount of adhesive applied is not particularly critical; representative amounts range from about to percent by weight of the fabric. When the substrate is a polyester, e.g., polyethylene terephthalate fabric or tire cord, a pretreatment is applied before employing the teachings of our invention. Shoaf, US. application Ser. No. 320,605, filed Oct. 29, 1963, discloses pretreatment with a mixture of '(a) a polyepoxide and (b) an aromatic polyis'ocyanate 'or adduct thereof, optionally, with an overcoat of a resorcinol-formaldehyde resin and a vinyl pyridine copolymer latex mixture ('s'ee Example 11). Schwarz, US; application Ser. No. 509,436, filed Nov. 23, 1965, discloses pretreatment with a mixture of (a) 2-pyrrolidone, (b) polyepoxide,'(c) alkaline catalyst and (d) optionally." a blocked isocyariate or formaldehyde (see Example 12). The polyepoxide is preferably a condensation product of epiehlorohydrin and glyce501; however, the glycerol can be replaced with bisphenol-A (e.g., in Araldite 6084 M1. C., epoxide equivalent of 935 Details concerning ranges and modifications of components are set forth in the above-identified applications, the teachings of which are incorporated herein by reference. 7

The a-olefin hydrocarbon copolymers are compounded with suitable curing agents before being bonded to the coated substrate. Typical curing aids used are sulfur, zinc oxide, and curing accelerators. Those skilled in the art can select by routine empirical experiments the best cofnbinations of accelerators when curing a particular assembly. In addition tothe above-described components the a-olefin copolymer may include such optional components as conventional antioxidants. It is to be understood that,

various modificationsof the sulfur curing procedifrres may be employed depending upon the stock. Various proce; dures and modifications of sulfur curing are more particu larly described in Encyclopedia of Chemical Technology, Kirk and Othmer, published by Interscience Encyclopedia. Inc., New York, 1953, vol. 11, pages 892-927; Principles of High-Polymer Theory and Practice, Schmidt and Marlies, published by McGraw-Hill Book Co., New York, 1948, pages 556566 Chemistry and Technology of Rubber, editedby M. Morton, Reinhold Publishing Corp, New York, 1959, pages 93-129; TheApplied Science of Rubber, edited by W. J. S. Naunton, Edward Arnold Ltd, London, 1961 pages 346-4l3, 9921099.

The adhered composite article 'is finally obtained by heating the curable assembly under pressure. Temperatures generally range between about 160 C. with about C. ,and C. being preferred. Cure times are not critical and can range from between about 10 minutes and 2 hours without adverse effect on the adhesion obtained. The cure time will vary inversely with the temperature, higher temperatures requiring shorfer cure times. Thoseskilled in the art will select the particular conditions needed for optimum results basedpn such' considerations as the conditions recommended in the art for the particular curing agents being used, etc. Dur ing the cure, pressure may be applied as desired.

The invention will now be described with reference to the following examples of specific embodiments thereof wherein parts and percentages are by weight unless otherwise specif ed.

EXAMPLE 1 ii (A) Preparation of chlorosulfonated polyethylene latex A chlorosulfonated polyethylene is selected containing about 26% chlorine and 1% sulfur. prepared from linear polyethylene having a melt index of. about 4.

An emulsion is prepared by adding 425 grams of a 5.9% solution of the chlorosulfonated polyethylene in carbon tetrachloride to a solutiorr of 2 grams of sodium salt of lauryl 'alcohol sulfate (commercially available from Du Pont as Duponol ME.dry surface active agent) in 125 ml. of water and 36 ml. of isopropanol at 25 C. in a high shear mixer. The resulting emulsion is distilled at reduced pressure at about 4050 C. to remove the carbon tetrachloride and some of the water. The resulting latex contains about 20-25% solids and has a pH of about 2.5 to 4at 25 C.

(B) lreparation of adhesive compositin A solution of 5.5"grams of resorcinol and 5.7 ml. ef 37% aqueous formaldehyde in 27.5 ml. of water is prepared at 25 Csand allowed to stand for about 4 to 6*hours at 25 C. The pH of this composition is about 3-4. To 5 grams of this composition at 25 C. are added 30 rnl. of the chlorosulfonated polyethylene latex and 3 grams of a 20% dispersion of zinc oxide in water. The resulting composition has a pH of about 6.7 to 7.4 at 25 C. It is allowed to stand at 25 C. for about 6 hours before being used'as an adhesive. (It would be preferred to allow it to stand for about 24 to 30 hours.)

(C) a-Olefin hydrocarbon elastomer An ethylene/propylene/1,4-hexadiene copolymer is employed which is made in accordance with the general procedures of US. Patent 2,933,480. Representative samples of this copolymer contain about 42% propylene and 4% 1,4-hexadiene monomer units by weight and exhibit a Mooney viscosity (ML4/250 F.) of about 70.

The elastomeric copolymer is compounded as follows on a rubber roll mill:

Component: Parts tX-O1fil'l hydrocarbon elastomer 100 HAF carbon black 50 Naphthenic petroleum oil 20 Zinc oxide 5 Tetramethylthiurani monosulfide 1.5 Z-mercaptobenzothiazol (MBT) 0.5 Sulfur 1.0

(D) Adhesion of elastomer to fabric The filament nylon fabric used is a plain weave with 6 at room temperature. The resulting composite articles are tested as described in the reference, typically display adhesive strengths of about 17.5 lbs. at 25 C. and about 12.5 lbs. at 100 C.

The cord adhesion and fabric adhesion results are essentially the same if the above procedure is repeated substituting a resorcinol formaldehyde resin wherein the mole ratio of formaldehyde to resorcinol is increased to 2:1.

EXAMPLES 2 THROUGH 9 TABLE I Tire cord adhesion Chlorosulfonated PE Dip H-pull values (lbs.) Fabric, Melt picku Dip pickup, adhesion index percent S Percent 01 wt. percent 25 C. 100 C. wt percent lb./in

a count of 60 x 40 (obtainable as Style SN-7 from Wellington Sears, 111 W. 40th St., New York 18, N.Y.). The spun fabric used has 48 warp ends and 36 pick ends and weighs 9.9 oz./sq. yard. The fabric is scoured with detergent to remove finishing agents, sizes, etc.

The scoured filament nylon is coated with coating composition prepared in Part B above by means of a paint brush. It is then dried for minutes in a vacuum oven at 100 C.

The coated nylon is then pressed against an 80-mil thick sheet of the sulfur-curable ethylene hydrocarbon elastomer of Part C. A 3" x 1%" piece of cellophane is placed at one end of the elastomer to facilitate subsequent separation of the elastomer and the fabric for testing. The elastomer is supported by 10-oz. cotton duck to provide stability. The assembly is then cured at 160 C. for 30 minutes under a pressure of 200-250 p.s.i. The peel adhesion of the resulting composite article typically displays an adhesive strength of about 36 lbs/linear inch at 25 C. As determined on an Instron tester by measuring the force necessary to separate a 1" wide piece of the fabric from the elastomer at a head speed of 2/min.

(E) Adhesion of elastomer to cord Nylon tire cord is coated by continuously running it through the coating composition prepared in Part B above at about 3 ft./rnin. and then through a 2-ft. column where it is contacted with a stream of air heated to about 135 C.

The coated nylon cord samples are then used to conduct single-cord adhesion tests or H-pull tests as described in India Rubber World, 114, 213-17 (1946). The coated cord samples are molded as described in the reference into the sulfur-curable ethylene hydrocarbon elastomer which was compounded as described above and the assemblies cured for 40 minutes at 160 C. under a pressure of 550 p.s.i., starting with the mold As can be seen from the table, both the fabric and tire cord adhesion values are the highest when the chlorosulfonated polyethylene contains about 15-20% chlorine.

EXAMPLE 10 This example illustrates a one-step preparation of adhesive composition (A) An aqueous composition is prepared at 25 C. by adding the following components successively without allowing any aging time to elapse between the successive addition: 5.7 ml. of water; 1.1 grams of resorcinol; 1.18 ml. of 37% aqueous formaldehyde; 46 ml. of a 21% solids chlorosulfonated polyethylene latex prepared according to the procedure of Example 1; and 3.0 grams of a 33% dispersion of zinc oxide in water. The molar ratio of resorcinol to formaldehyde is 121.5. The pH of the mixture resulting is about 7.4. This composition is allowed to stand for about 3 to 7 hours at 25 C. before being used to coat the nylon fabric. (It would be preferable to age for about 30 hrs.) I

(B) A second composition is prepared in the same way except that equal molar proportions of formaldehyde and resorcinol are employed. After nylon tire cord and fabric have been coated and dried and composite articles have been prepared and cured as described in Example 1, parts D and E, the resulting adhered articles are tested in accordance with the procedure of Example 1 for cord and fabric adhesion. The table which follows gives the results.

7 EXAMPLE 11 (A) Preparation of the polyester pretreating compositions A slurry is prepared in the following manner. Add 0.24 lb. of a paste containing 75% by weight of dioctyl sodium sulfosuccinate and 25% water (commercially available from American Cyanamid Company as Aerosol OT) to 6.26 lbs. of warm water and mix at slow speed until completed dissolved (approximately minutes are required). Add the solution obtained to 16 lbs. of water at room temperature while mixing at slow speed. To the resulting solution add 7.50 lbs. of blocked diioscyanate, the diphenyl ester of 4,4-methylene-dicarbanilic acid (commercially available from Du Pont as Hylene MP organic isocyanate), and mix at slow speed until completely dispersed. The resulting composition is added to a 4.6 gallon ball mill containing approximately 20 lbs. of grinding media. Ball mill the composition on a roller mixer for 72 hours. The resulting composition is ball milled or mixed one hour before using in order to assure complete suspension; high speed mixing is avoided to prevent foaming. The slurry of blocked polyisocyanate containing 25 solids.

Add 0.14 lb. of epoxy resin, the condensation product of glycerine and epichlorohydrin, having an average molecular weight of about 300 and an epoxide equivalent of 140-165 (Epon 812), to 8.37 lbs. of water at room temperature and mix slowly. Prepare a solution containing 2% solids by adding 5 grams of gum tragacanth to 245 grams of water at room temperature; mix until completely dissolved (approximately 5 minutes required). Add about 0.20 lb. of the 2% gum solution (freshly mixed) to the epoxy resin-water solution while mixing slowly. Finally, add 1.29 lbs. of the blocked isocyanate slurry to the resulting mixture and mix for 3 min. at slow speed.

The overall composition contains 5.0% solids and is made in the following proportions: 8.37 parts of water (room temperature); 0.14 part of epoxy resin; 0.2 part of the 2% solution of gum tragacanth; and 1.29 parts of a 25% slurry of blocked organic isocyanate. This dip is not stable and the solids will settle out very quickly when not agitated or circulated. When in use, the dip must be circulated using a pump or agitated manually every 5 to minutes. For best results this dip should be made fresh each day it is to be used.

A resorcinol-formaldehyde (RFL) dipping composition is prepared in the following way. 1.38 pounds of resorcinol, 2.39 lbs. of 1.57% aqueous sodium hydroxide, 2.02 lbs. of 37% aqueous formaldehyde, and 27.8 lbs. of water (at 75-78 F.) are stirred together and allowed to age for 6 hours. Then the resulting composition is mixed with 30.50 lbs. of 41% Gen-Tao (a terpolymer of butadiene/styrene/2-vinyl pyridine), 7.64 lbs. of water at 75 F. and 1.42 lbs. of 28% aqueous ammonium hydroxide. The final composition is allowed to age at least 12 hours before use.

Type 68, 840/2 Dacron polyester tire cord is dipped in the first pre-treating composition described above and dried for 1.3 minutes at 450 F. The pick-up (dry weight) is about 0.4 percent. The coated cord is then dipped in the resorcinol-formaldehyde composition and dried for 1.3 minutes at 450 F. The pick-up (dry weight) of the second coat is about 4 percent.

(B) Preparation of chlorosulfonated polyethylene latex dip A chlorosulfonated polyethylene is selected containing about 20% chlorine and 1% sulfur. A 12.5% solids solution is prepared by dissolving this chlorosulfonated polyethylene and 0.1 phr. (parts/100 parts of polymer) dinitrotoluene in a 88/12 benzene/isopropanol mixture. Two parts of this solution are then added to one part of water containing 8 phr. of sodium alkyl benzene sulfonate (Nacconol NRSF) and 0.25 phr. of sodium nitrite in a high shear mixed at C. Solvent is removed from the resulting emulsion with steam at atmospheric pressure to give a latex. After 0.8 part of ammonium alginate has been added for each parts of latex solids, the composition is allowed to cream by standing for several days at room temperature. A 53% solids latex resulted.

The 53% solids latex is diluted to 41% solids with water.

A phenol-aldehyde resin composition is prepared at 2530 C. by dissolving 44 parts of resorcinol flakes in 88 parts of distilled water, and adding slowly with stirring 23.8 parts of a 37% aqueous formaldehyde solution. After two minutes mixing, the resulting composition is ripened by storage at 25-30 C. for one hour. Then 155.8 parts are slowly added to 286 parts of the (41% solids) latex with stirring. Dilute aqueous sodium hydroxide is added to adjust the pH (at 25-30" C.) to 7.3. Four days storage follows before clips are made.

The polyester tire cord treated as in Part A above is dipped in the resin-latex composition; the pick-up after drying under nitrogen (at 210 C. for 0.7 minute) is about 4.8% based on the weight of the cord.

(C) Preparation of substrate composition The substrate composition is a carcass stock compounded according to the following recipe:

Component: Parts wOlefin hydrocarbon elastomer (Ex. 1) 100 HAF carbon black 80 Naphthenic petroleum oil (Necton 60) 47.5 Zinc oxide 5 Tetramethylthiuram monosulfide 1.5 Z-mercaptobenzothiazole 0.75 Sulfur 1.5 Stearic acid 1.0

(D) Preparation of adhered assembly The coated polyester cords are cured against the substrate composition at C. for 40 minutes at 3500 lbs./ sq. in. pressure. The adhesion of the resulting cured assembly is then measured by the H-pull test, and it is typically found that the assembly will display about 18 lbs. at room temperature and 12 lbs. at 100 C.

If for comparison, the above procedure is repeated except that the coating of this invention described in Part B is omitted, the H-pull values typically drop to 8 lbs. and 5 lbs., respectively.

EXAMPLE 12 (A) Preparation of polyester pretreating composition Dissolve 20 parts by weight of the diphenyl ester of 4,4-methylene-dicarbanilic acid (Hylene MP organic isocyanate) with stirring in 100 parts of 2-pyrrolidone. Then add, again with stirring, 20 parts of the epoxy resin (Epon 812) and 3 parts of 10% by weight aqueous sodium hydroxide. The ratio of pyrrolidone to Epon 812 to Hylene MP is 5:1:1. Use the fresh composition thus made.

Polyester tire cord (Dacron tire cord 840/2/2; Type 68) is coated with the pretreating composition described above and cured in a dielectric field while being simultaneously drawn to yarn at about 1000 yards/minute windup speed.

(B) Application of chlorosulfonated polyethylene latex dip The polyester tire cord, coated with the pretreating composition as described in Part A above, is then dipped in an aqueous resin-latex adhesive composition similar to hat of Part B of Example 11 (except that the pH was not adjusted before use) and dried for one minute at 435 F. The percent pick-up (based on the pretreated cord weight) is about 15.

9 (C) Preparation of adhered assembly The carcass stock described above in Part C of Exampic 11 is cured against the coated polyester tire cord for 40 minutes at 160 C. It is typically found that the assembly will display H-pull" values of about 13 lbs. at room temperature and 9 lbs. at 100 C.

When, for comparison, the coating of this invention set forth in Part B above is omitted, the values typically drop to about 4 lbs. and 3 lbs., respectively.

EXAMPLE 13 The following example illustrates the use of a precondensed resorcinol-formaldehyde resin in the preparation of an adhesive composition for nylon cord and fabric.

4.0 parts of Penacolite R-2170 (a precondensed resorcinol-formaldehyde resin of 75% solids content from Koppers Co.) is dissolved in 70 parts of water containing 0.12 part of sodium hydroxide and 2.6 parts of 37% aqueous formaldehyde solution is added. The solution is allowed to stand for 2 hours at 25 C. and is then added to 51 parts of a 47% solids latex of a linear chlorosulfonated polyethylene, containing 20% chlorine and 1% sulfur, and 20 parts of water. The resulting adhesive dip has a pH of about 7.7 and after aging for 1 hour at 25 C. is used to coat nylon cord and fabric.

Typical adhesion results using a stock of the following composition:

EXAMPLE 14 The following example illustrates an adhesive composition for rayon.

A solution is prepared containing 2.76 parts of resorcinol, 4.1 parts of 37% aqueous formaldehyde solution, and 4.7 parts of 7.8% sodium hydroxide solution in 55.6 parts of water. This solution, which has a pH of about 9, is allowed to stand for about 6 hours at 25 C. To 31.4 parts of this solution are then added 26.6 parts of a 45.5% solids latex of chlorosulfonated polyethylene and 12 parts of water. The adhesive mix which has a pH of about 9 is allowed to stand at 25 C. for 16-24 hours before being used to coat rayon tire cord (1100/2). Typical adhesion results using the elastomer stock of the same composition as in Example 13 are as follows:

Dip pickup (percent) 8.9 H-pull (lbs.) at:

10 (88/12) with 60 parts of water containing 0.029 part of sodium nitrite. The solvent is removed by contacting the emulsion with steam and the resulting dilute latex is concentrated to 47% 'solids by creaming with ammonium alginate.

The improvement obtainable by this invention enables u-olefin hydrocarbon copolymers to be firmly bonded to substrates such as tire cord or fabrics by a very simple and safe operation. It is quite unexpected that the presence of the phenol-aldehyde resin solution in the dispersion with the chlorosulfonated polyethylene did not adversely affect the properties of the latter.

As many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims, and all changes which come within the meaning and range of equivalence are intended to be embraced therein.

What is claimed is:

1. An adhesive composition suitable for single-dip bonding of sulfur-curable, chain saturated hydrocarbon copolymers to polyamide or cellulosic substrates which comprises an aqueous dispersion of (a) from about 2 to 6 parts by weight of a chlorosulfonated polyethylene having from about 10 to about 20 weight percent chlorine and from about 0.5 to 3 weight percent sulfur, the polyethylene before chlorosulfonation having a melt index of from about 0.07 to 4 decigrams/min.; and (b) 1 part by weight of a base-condensed resorcinol-forrnaldehyde resin wherein the weight ratio formaldehyde/resorcinol is from about 0.7 to 2.

2. An adhesive composition according to claim 1 wherein the chlorosulfonated polyethylene has from about 15 to 20 weight percent chlorine and from about 0.7 to 3 weight percent sulfur.

3. An adhesive composition according to claim 2 wherein the chlorosulfonated polyethylene has about 20 weight percent chlorine and about 1 weight percent sulfur.

4. A process for preparing an adhesive composition suitable for single-dip bonding of sulfur-curable, chain saturated hydrocarbon copolymers to polyamide or cellulosic substrates which comprises (a) forming an aqueous dispersion containing from about 2-6 parts by weight chlorosulfonated polyethylene, the said chlorosulfonated polyethylene having from about 10 to about 20 weight percent chlorine and from about 0.5 to 3 weight percent sulfur, said polyethylene having before chlorosulfonation a melt index of from about 0.07 to 4 decigrams/min.; and (b) forming one part by weight of resorcinol-formaldehyde resin in situ in the aqueous dispersion by adding resorcinol and formaldehyde directly to the dispersion under basic conditions, the weight ratio formaldehyde/ resorcinol of said resin being from about 0.7 to 2.

5. The process of claim 4 wherein the said chlorosulfonated polyethylene has from about 15 to 20 weight percent chlorine and from 0.7 to 3 weight percent sulfur.

6. The process of claim 4 wherein the said chlorosulfonated polyethylene has about 20 weight percent chlorine and about 1 weight percent sulfur.

References Cited UNITED STATES PATENTS 3,276,948 10/1966 Gallagher 156-335 3,366,508 l/1968 Gallagher 260847 SAMUEL H. BLECH, Primary Examiner JOHN C. BLEUTGE, Assistant Examiner US. Cl. X.R. 

